These types of capsules have been known from the 1970's. Beverage capsules comprise a container portion that houses a dose of at least one extractable product, generally ground coffee, but also tea herbal extracts and similar products. The capsules also comprise a portion that interacts with a brewing device to prepare the required beverage. The typical brewing device comprises a boiler, an enclosing member, or receptacle, intended to cooperate with the capsule and a pump or similar means so that the brewing liquid or solvent, usually but not exclusively hot water under pressure, can be fed to the capsule for the extraction of the beverage from the dose of product contained therein.
In a known beverage preparation process, a capsule is placed into the receptacle of the brewing device and is fed with the brewing solvent, such as hot water. The injected solvent passes through the capsule and thus creates by dissolving the soluble solids contained in the foodstuff or solubilising the powder contained in the capsule or otherwise diluting the liquid concentrate contained therein. In other words the injection of the solvent inside the capsule allows for the constitution of the beverage from the ingredient enclosed therein. The beverage thus formed exits the capsule to reach a beverage collector or outlet spout and then a cup or a container.
The injection of the brewing liquid may be obtained by providing a surface of the capsule where holes are present, usually these holes being placed on the water inlet surface of the capsule. This solution, though, results in coffee powder to be spilled outside the capsule during handling or transport and in general in a faster oxidization of the foodstuff. For the above reasons it is preferred to use closed or sealed capsules in which the inlet means, i.e. the at least one opening for the brewing liquid to penetrate into the capsules, is created on an inlet surface of the capsule, preferably its inlet wall when the capsule is used. For this purpose the brewing device is provided, usually at its water inlet wall, with piercing means, usually in the form of one or more protruding parts, such as needles or blades, that are moved with respect to the capsule (or viceversa) for perforating the inlet surface or inlet wall of the capsule, generally the piercing means protrude, at least in part, through the inlet surface. Openings, or holes, formed by the piercing means allow the passage of the brewing liquid inside the capsule.
Feeding of brewing hot water by piercing the inlet wall of the capsule is a method well known in the art and is disclosed in several prior art documents.
U.S. Pat. No. 2,778,739 discloses a package for beverage infusion having a body and an upper cover that is pierced by protruding elements of the brewing device. A similar concept is disclosed in U.S. Pat. Nos. 2,968,560 and 3,607,297.
Recently, some problems have been encountered by using capsule made of plastic polymers instead of capsule made of more rigid and thinner material, such as aluminium. Capsules made of plastics can be difficult to perforate so that full piercing of the capsule wall is not achieved, thereby no solvent e.g. hot water can be injected in the capsule, or only a partial perforation is achieved, thus providing an irregular and unsatisfactory distribution of the solvent inside the capsule and equally irregular quality of the beverage in the cup.
Therefore there is the need of obtaining a good perforation of capsules, especially of capsules made of materials softer than aluminium, such as standard thermoplastic materials, e.g. PE or PP polymers, or degradable plastics or so called bio-materials, e.g. PLA.
For facilitating the perforation by piercing means of the brewing device plastic capsules have been provided with reinforcing members, for example as disclosed in the international patent application WO2011/027259.
WO2011/027259 discloses a capsule having reinforcing means provided on its lateral wall in the form of a plurality of circular ribs, or an annular protruding member, and similar.
These solutions require, ceteris paribus, a higher mass of thermoplastic material during the production process, resulting in a heavier, less environmental-friendly capsule. Also, in any case, reinforcing members provided on the outer wall of the capsule may prove only partially effective for the reinforcement of the inlet wall in the areas where it has to be perforated.
EP2287090 discloses a capsule having an inlet wall provided with a section thinner than the rest of the wall, in the position where the piercing elements of the brewing apparatus will impinge, so as to facilitate the penetration of blades of the water injection device. Such thinning of the walls allows, though, for the deformation of the walls. For this reason reinforcement ribs are provided, too, extending both on the inlet wall and on the side wall of the capsule, thus avoiding undesired deformation of the capsule when piercing means of the brewing device exert a perforation force on the inlet wall of the capsule. However, reinforcing members that are disposed on the inlet wall of the capsule need to be dimensioned, positioned and oriented in an accurate manner so as to not be impinged by the piercing means of the capsule. In fact, should these ribs be contacted by the piercing blades of the brewing device, they would prove very hard if not impossible to perforate due to the additional material that determines an increase of the thickness of the inlet wall of the capsule in correspondence of the ribs.
WO2010/041179 shows a sealed capsule having an inlet wall and a lateral wall (see FIG. 2) wherein a sunken portion is provided on the inlet wall; the sunken portion extends on the inlet wall only and ends at the beginning of the lateral wall (see FIGS. 5 and 6). This sunken portion of the wall is intended to be a reinforcing element that cooperates with a corresponding radial ridge on inlet wall. The reinforcing effect of the sunken portion is almost inexistent.
WO2012/080501, that was filed before and published after the priority date of the present application, discloses a capsule where the inlet wall, or base—to use the terminology adopted in the document—is provided with a reinforcement zone arranged circumferentially on the base as a plurality of recesses; all the recesses are located and contained within the base. The recesses have two walls forming an angle of about 90 degrees with each other, wherein one of the walls is vertical, i.e. is parallel to the rotational vertical axis of the capsule and the other is substantially horizontal. However, the reinforcing effect of this structure is very limited, actually non existent if the capsule is thermoformed, so that the amount of deformed and not-opened capsules is very high and the opening of the capsule is not carried out in a reliable way.
It is an aim of the present invention to solve the above problems and to provide a capsule that can be pierced in a simple and effective manner, and to limit the number of reinforcing members on the upper inlet wall of the capsule.
Another aim of the present invention is to provide adequate reinforcement to the area where the inlet means need to penetrate the capsule wall, yet minimising the increase of capsule material needed to achieve such objective.
Another aim of the present invention is to provide a capsule that can be produced in a simple manner without the need of providing a portion of reduced thickness on the inlet wall of the capsule depending on the position of the piercing means of the brewing device.